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The Ultimate Four Eyed Fox 5-Lug Conversion Thread

We've been seeing a number of threads pop up asking 5-Lug conversion questions. I will post what I know, but I need everyone to contribute what they can. I will continue to edit this post to compile all of the information you provide into one post.

Please correct any mistakes I have made and contribute anything you feel is necessary so that I can compile your information into this post.

Front Calipers/Spindles/balljoints
99-04 dual piston PBR calipers are better than 94-98 Calipers. If using 94-95 spindles, grinding/modification will need to be performed on the spindle to use PBR calipers with 94-95 spindles. 99-04 Calipers will bolt to a 96-98 spindle without modification, but these spindles will push your wheels out further.

All 94-98 v6/GT calipers are the same. All 99-04 v6/GT calipers are the same. All calipers from 94-04 can be used on a fox body with SN95 spindles.

96-98 spindles push your front wheels out further than 94-95 spindles. Are 99-04 front spindles the same as 96-98 spindles? Can anyone provide dimensions and how much the different spindles push the wheels out?

A-Arms"All arms from 79-93 (except SVO) are a direct swap. The FRPP arms are the same as the 87-93 arms for the 5.0 cars with low friction ball joints as well as a gusset welded to them. The 94-95 arms are the same as the 87-88 Thunderbird Turbocoupe arms and are 3/4" longer than the 79-93 arms." (Travis T)

Rear Calipers/Brackets
All 94-04 V6, GT, and Cobra rear calipers are all the same. 94-04 V6/GT rear rotors, pads, and caliper brackets are exactly the same. The difference with the Cobra brakes is a larger rotor, thinner brake pads, and a different caliper bracket that will position the v6/GT caliper over the larger rotor.

Rear Brake Lines
For an OEM fit/finish, 94-95 GT axle hard lines are the perfect size for a fox body rear disc conversion. No bending, cutting, or flaring is needed when you use 94-95 rear hard lines. 94-95 GT rear soft lines should be used and can be purchased brand new from Napa for about 15 dollars per side.

You can use your stock fox body rear hard lines, but they are too long and will need to be bent out of the way, or cut and reflared.

94-95 V6 rear hard lines, 96-98 v6/gt rear hard lines are not the same as 94-95 GT hard lines and require some modification to be used.

Proportioning valve
SN95 V6/GT master cylinder
Gut the stock prop valve and replace the end cap on the proportioning valve with the FRPP end Cap(part number M-2450-A) and purchase a Wilwood or summit adjustable proportioning valve.

Master Cylinder
To keep things easy, you can use any SN95 V6/GT master cylinder. (Other master cylinders can be used.)

Brake Booster
larger brake booster from a 94-95 V8 or V6 or a 96-98 V6 or a 93 Cobra.
It is impossible to install a larger brake booster into an 86 and older fox body without massaging the strut tower. Do not beat the strut tower with a sledge hammer. Proper massaging procedures should be used to avoid damaging the structural integrity of the strut tower. Improper massaging techniques will produce negative results and can lead to the sheet metal cracking.

The SN95 brake boosters have a stud pattern that makes it difficult to install the booster onto a pre-87 Fox body. It's not impossible, but it is significantly more difficult. You will need to massage the strut tower and significantly elongate the brake booster holes in the firewall.

You can purchase a remanufactured 93 Cobra brake booster from a carparts store like Kragen. The manufacturer is Cardone. This brake booster is the same size as the SN95 brake booster but retains the fox body brake booster stud pattern. You will need to massage your strut tower. You may need to elongate the holes in the firewall slightly, depending on how much your clearance your strut tower.

5-Lug rear drum brakes
You will need axles from the following vehicles
2 passenger side aerostar axles
or
driver side Bronco II? (which years and sides?)
or
driver side ranger axles? (which years and sides?)
Aerostar drums are 10 inch. If you want to upgrade to 10 inch rear drums, snag the aerostar drums and backing plates as well. Otherwise, you will need 9 inch 5 lug rear drums from the above year Bronco II or Ranger

A-Arms
What are the differences in size between 79-86 a-arms, 87-93 a-arms, 94-05 a-arms? Are the FRPP A-Arms the same as OEM 94-04 A-Arms?

All arms from 79-93 (except SVO) are a direct swap. The FRPP arms are the same as the 87-93 arms for the 5.0 cars with low friction ball joints as well as a gusset welded to them. The 94-95 arms are the same as the 87-88 Thunderbird Turbocoupe arms and are 3/4" longer than the 79-93 arms.

For the front, the cheap way that retains the fox spindle and brakes is to run a 2wd 84-90 ranger front rotor (for all 2.3 cars and v8 cars >1986) or 85-86 SVO/Mark VII front rotors (1987+ V8 cars)

In the rear, ONLY the 7.5" axle equipped rangers/areostars will work, if it has 10" drums (7.5" axles have 9" foxbody size drums, which swap directly over) it has an 8.8" axle with more offset and the axles don't fit. the 28 spline units in the 8.8 and 7.5 axles are the same strength, the 7.5" just has a smaller ring and pumpkin.

A word of caution, if you swap rotors to get 5-lug, your wheel choices will be limited as after 1998 Ford phased out greasable hubs and went to the sealed hub design with no spindle cap, thus making their wheel designs shallower (your flashy cobra R's won't fit over the ranger or SVO hubs) I know the 97-98 cobra wheel, 16" pony, 17" tri-bar and the v6 wheels will fit, others its hit and miss.

The e-brake cable #'s for the SN95 rear disc swap are F3ZZ-2A635-A. Two are required. 1993 Cobra Units.

Those cables are only for a 1993 car. You need two FMS M2809A rear cables for all 1979-1992 cars. If you have a 1979-1986? (whenever they changed the e-brake handle to the ratchet gear type) you do not need the front FMS M2810A cable, all 1987-1992 cars will need the front cable and will need to modify their e-brake handle ratchet gear.

The e-brake cable #'s for the SN95 rear disc swap are F3ZZ-2A635-A. Two are required. 1993 Cobra Units.

This is specific only to the 93 Model cars. 79-92's use the FRPP cables M-2809-A. They are $27.95 each, 2 are required per car. The 79-86 cars do not need the intermediate cable M-2810-A. That small cable is specific to the 87-92 cars.

The plug for the proportioning valve is the M-2450-A. I've read of a possible design change due to the newer proportioning valves going to a metric thread. I've got one from about 7 years ago that I can post a pic of. I'll try to make note to do that as well as gather a pic of the newer version. This directly affects a majority of the FoxChassis cars because of their age.

I've got the specific adapter size for the passenger side SN95 hose on a Fox. I kept the little package that it came in so I'll have a specific brand part number and sizing. I'll post it when I get home. It's still on my workbench.

Are there any big problems if you dont gut the stock proportioning valve? i did a 5 lug conversion to my 83 and used the stock prop valve with no modifications and the stock booster..i did put on an 85 lincoln towncar master cylinder..and the only problem ive ran into is that the pedal is sometimes hard to press..its not impossible to press and stop just kinda hard unless im cruising at a higher RPM or i rev the motor to raise RPMs...anyone have any advice on this?

Anyone doing the rear conversion will need a couple of spacer rings that fit between the axle pilot and the rear disc rotor to center the rotor if a person J/Y sources the Aerostar/Ranger axles. Otherwise, they'll have to get a pair of 5 lug drilled 79-93 length axles but with the SN95 center pilot.

Can 94-95 front control arms be used in place of 79-93 ones? They are quite a bit cheaper than the fox arms, and although I hear they are a little longer, aren't the control arm mounting points positioned more inward on 79-90 foxes? Wouldn't this make the front track width closer to what a 90-93s track width is? I need new ball joints and bushings, and the sn95 control arms are quite a bit cheaper than the fox control arms, so if possible I would like to use the cheaper arms.

Updates have been made. Thank you so much to for all of the contributions. Once again, if anything in my original post is left unanswered, if i've left out any information, or if anything is inaccurate, please let me know.

I don't have too much information on the non-SN95 5 lug upgrade options for our four eyes. Some people have begun to post some information. If anyone has more information on whats needed for non-sn95 5 lug upgrades, please post what you know.

Thanks again, this thread is turning out to be a really great source of information.

On my 86 I ran 03 lower control arms and had to update the inner and outer tie rods to longer ones (03 as well) if not I would not have had enough thread.
I would recomend to anyone that is wanting the rear disc's; to refit the SN95 calipers onto there original diff as wider tire range is available without custom rims.